THE FRACTURED SEA BASIN 81 



The slight sketch we have just given treats only of 

 appearances, and we may now venture on a few words 

 of explanation. 



The origin of the Lipari isles is directly connected 

 with their situation. They occur within an area of the 

 earth's crust which has been fractured by a series of great 

 cracks, and has then sunk down towards the interior. 



FIG. 16. The last stage of the Eruption, from a slightly 

 different point of view. (From a photograph.) 



The cracks are arranged in a system which recalls that 

 produced when we batter in the end of an egg with a 

 spoon. There is a large peripheral rent forming part of 

 a circular arc (Fio\ 8). This passes through the southern 

 extremity of Italy and the north of Sicily ; from a point 

 within this four other rents radiate outwards, crossing 

 the peripheral one ; on these the Lipari Isles, w r hich are 

 volcanic, stand ; and Etna rises immediately over the 



7 



